Galileo's bombshell that the earth is not the axis around which the universe revolves but a mere satellite of the sun must have disturbed Catholic minds at that time and the Fathers of the Church must have seriously considered its effect on the good of souls, their prime duty. (faith.org.uk)
To my mind - and I WAS BROUGHT UP TO BELIEVE THAT THE PRIME DUTY OF A DEFENDER IS TO DEFEND; THE CLUE IS IN THE NAME — this man could not defend Fort Knox from an attack by an aged snail with a pea shooter! (justarsenal.com)
In many tactical setups, their prime duty is to provide width on the flanks, allowing the wide attackers to venture to central positions and pose more of a direct threat to the opponent's goalkeeper. (squawka.com)